This application seeks support for a five-year study of relational discrimination learning processes in individuals with severe to moderate intellectual disabilities. The overall goal is to complete the development of an effective, integrated set of programmed methods for teaching relational discriminations to our subject population. Work accomplished in the first grant period has made substantial progress toward this goal. Further, it led to promising new methods for teaching the first instances of generalized identity (same/different) and arbitrary (symbolic) matching-to-sample to individuals who do not learn with standard teaching procedures. Results of our studies also pointed to stimulus control processes that had been only poorly appreciated in past work. Studies proposed for the next grant period will follow up and further analyze these processes. The Specific Aims of Project 1 are to: (1) identify the critical features of procedures that have proven effective in teaching relational discrimination; (2) determine whether newly developed programmed procedures for teaching identity matching to sample can be adapted to teach arbitrary matching; (3) evaluate the effectiveness of sample stimulus control shaping (i.e., making gradual changes in formal stimulus characteristics) for teaching arbitrary stimulus-stimulus relations to individuals who do not learn such relations readily; (4) develop assessment procedures that could potentially maximize the efficiency of sample shaping programs by pretests that empirically determine the effective program steps for each subject individually; (5) begin to consolidate the sample shaping assessment and teaching procedures into an automated, computer-managed program of instruction.